Development of a generic method for the determination of protonpump inhibitors by capillary zoneelectrophoresis

A generic capillary zone electrophoresis method was developed for the analysis of four proton pump inhibitors: omeprazole, pantoprazole, lansoprazole and rabeprazole. During preliminary analysis screening of phosphate buffers at different pH levels was performed, in order to determine the optimum pH domain suitable for the simultaneous determination of all studied compounds. A face centered central composite design was employed for the optimization of separation conditions. The effect of buffer concentration, pH and applied voltage was studied; resolution between peaks and migration time of the last compound were considered as responses. Other factors as system temperature, injection parameters, capillary length, were held constant during the optimization process. The optimized conditions consisted of 40mM phosphate background electrolyte at pH 5.0, +25 kV applied voltage and 20 °C temperature. The migration order of the analytes was as follows: rabeprazole, omeprazole, lansoprazole and pantoprazole. Full resolution of all analytes was achieved within 9 minutes. The method was validated and proved to be suitable in terms of repeatability, sensitivity, linearity, accuracy and robustness. Determinations from commercially available pharmaceutical formulation were performed for omeprazole; good reproducibility and recovery were obtained

Simultaneous determination of atorvastatin and ezetimibe from combined pharmaceutical products by micellar electrokinetic capillary chromatography

A rapid and sensitive micellar electrokinetic capillary chromatography method with UV photodiode-array detection was developed for the simultaneous determination of atorvastatin and ezetimibe in fixed dose drug combination. Experimental conditions such as buffer concentration and pH, surfactant concentration, system temperature, applied voltage, injection parameters were optimized in order to improve the efficiency of the separation. The best results were obtained when using fused silica capillary (48 cm length X 50 µm ID) and 25 mM borate buffer electrolyte at pH 9.3 containing 25 mM SDS, + 30 kV applied voltage, 20 ºC system temperature. The separation was achieved in approximately 2 minutes, with a resolution of 7.02, the order of migration being atorvastatin followed by ezetimibe. The analytical performance of the method was verified with regard to linearity, precision, robustness and the limit of detection and quantification were calculated

Phenolic Content from Medicinal Plants and their Products Used in Veterinary Medicine

Objective: The aim of the study was to determine the content of polyphenols and flavonoids from sixteen selected medicinal plants from the spontaneous Romanian flora and fifteen tinctures obtained with propylene glycol

Chiral separation of lansoprazole and rabeprazole by capillary electrophoresis using dual cyclodextrin systems

Novel capillary electrophoresis methods using CDs as chiral selectors were developed andvalidated for the chiral separation of lansoprazole and rabeprazole, two proton pump in-hibitors. Fourteen different neutral and anionic CDs were screened at pH 4 and 7 in thepreliminary analysis. Sulfobutyl-ether-␤-CD with a degree of substitution of 6.5 and 10 atneutral pH proved to be the most suitable chiral selector for both compounds. Various dualCD systems were also compared, and the possible mechanisms of enantiomer separationwere investigated. A dual selector system containing sulfobutyl-ether-␤-CD degree of sub-stitution 6.5 and native ␥ -CD proved to be the most adequate system for the separations.Method optimization was carried out using an experimental design approach, performingan initial fractional factorial screening design, followed by a central composite design toestablish the optimal analytical conditions. The optimized methods (25 m M phosphatebuffer, pH 7, 10 mM sulfobutyl-ether-␤-CD/20 mM ␥ -CD, +20 kV voltage; 17°C tempera-ture; 50 mbar/3 s injection, detection at 210 nm for lansoprazole; 25 mM phosphate buffer,pH 7, 15 mM sulfobutyl-ether-␤-CD/30 mM ␥ -CD, +20 kV voltage; 18°C temperature;50 mbar/3 s injection, detection at 210 nm for rabeprazole) provided baseline separationfor lansoprazole (Rs= 2.91) and rabeprazole (Rs= 2.53) enantiomers with favorable migra-tion order (in both cases the S-enantiomers migrates first). The optimized methods werevalidated according to current guidelines and proved to be reliable, linear, precise, andaccurate for the determination of 0.15% distomer as chiral impurity in dexlansoprazoleand dexrabeprazole samples

Simultaneous determination of atorvastatin and ezetimibe from combined pharmaceutical products by micellar electrokinetic capillary chromatography

Abstract A rapid and sensitive micellar electrokinetic capillary chromatography method with UV photodiode-array detection was developed for the simultaneous determination of atorvastatin and ezetimibe in fixed dose drug combination. Experimental conditions such as buffer concentration and pH, surfactant concentration, system temperature, applied voltage, injection parameters were optimized in order to improve the efficiency of the separation. The best results were obtained when using fused silica capillary (48 cm length X 50 µm ID) and 25 mM borate buffer electrolyte at pH 9.3 containing 25 mM SDS, + 30 kV applied voltage, 20 ºC system temperature. The separation was achieved in approximately 2 minutes, with a resolution of 7.02, the order of migration being atorvastatin followed by ezetimibe. The analytical performance of the method was verified with regard to linearity, precision, robustness and the limit of detection and quantification were calculated

Classification and Lateralization of Temporal Lobe Epilepsies with and without Hippocampal Atrophy Based on Whole-Brain Automatic MRI Segmentation

Brain images contain information suitable for automatically sorting subjects into categories such as healthy controls and patients. We sought to identify morphometric criteria for distinguishing controls (n = 28) from patients with unilateral temporal lobe epilepsy (TLE), 60 with and 20 without hippocampal atrophy (TLE-HA and TLE-N, respectively), and for determining the presumed side of seizure onset. The framework employs multi-atlas segmentation to estimate the volumes of 83 brain structures. A kernel-based separability criterion was then used to identify structures whose volumes discriminate between the groups. Next, we applied support vector machines (SVM) to the selected set for classification on the basis of volumes. We also computed pairwise similarities between all subjects and used spectral analysis to convert these into per-subject features. SVM was again applied to these feature data. After training on a subgroup, all TLE-HA patients were correctly distinguished from controls, achieving an accuracy of 96 ± 2% in both classification schemes. For TLE-N patients, the accuracy was 86 ± 2% based on structural volumes and 91 ± 3% using spectral analysis. Structures discriminating between patients and controls were mainly localized ipsilaterally to the presumed seizure focus. For the TLE-HA group, they were mainly in the temporal lobe; for the TLE-N group they included orbitofrontal regions, as well as the ipsilateral substantia nigra. Correct lateralization of the presumed seizure onset zone was achieved using hippocampi and parahippocampal gyri in all TLE-HA patients using either classification scheme; in the TLE-N patients, lateralization was accurate based on structural volumes in 86 ± 4%, and in 94 ± 4% with the spectral analysis approach. Unilateral TLE has imaging features that can be identified automatically, even when they are invisible to human experts. Such morphometric image features may serve as classification and lateralization criteria. The technique also detects unsuspected distinguishing features like the substantia nigra, warranting further study